Currently I am using six rechargeable batteries for my Lego Mindstorms EV3.
A few seconds after I start a motor the EV3 gives a notification that that the battery is low.
I know that good batteries ...

I just bought a bulk lot of second-hand bricks and found this odd one inside. It has a black panel on one side and when pressed it plays a screeching sound. Through the transparent purple top I can ...